Method of preparing pulp



June 13, 1933 U.- S. M MILLAN METHOD OF PREPARING PUL? Filed Sept. 30, 1929 Patented June 13, 1933 mural) STATES PATENT OFFICE 'UEL S. MCMILLAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO MCMILLAN FIRETPROOF FIBRE (70., OF CHIOAGO, ILLINOIS, A CORPORATION OF ILLINOIS Mnrnon or rnnranrne PULP Application filed September 30, 1929. Serial No. 386,152.

This invention relates to a method of preparing pulp for the manufacture of paper and the like.

It is an object of this invention to provide a method for the preparation of pulp for use in the manufacture of paper that may be used either for the preparation of a mechanical pulp of higher quality than that of heretofore known ground wood pulp or in the preparation of a chemical pulp in a more economical manner than heretofore.

Other and further important objects of this invention will become apparent from the following description and appended claims.

The process of this invention is best illustrated in connection with the accompanying'drawing in which there is shown a side elevational view of an apparatus suitable for carrying out my process, with parts in section.

,The reference numeral 1 indicates a base upon which is supported a frame 2 having a top surface 3 suitably formed of metal. An open-bottom receptacle a is mounted upon said surface 3 for reciprocatin movement, said movement being efiected y means of a pair of links 5 pivotally'connected to one end of said receptacle t as at 6 and at the other end connected to a traveling belt or chain 7. Said chain 7 is trained over a pair of spaced pulleys 8 and 9, the pulley 9 being mounted upon a shaft 10 which also carries a pulley 11 driven by meansof a belt 12 from another pulley 13. A motor, or

' other suitable driving means 14 serves to drive the pulley 13 through pulleys 15 and 16 and belt 17.

A chamber 18 having hopper-shaped bottom walls 19 is disposed beneath the surface 3 on which said receptacle 4 is reciprocated. Within said chamber 18 are mounted a pair of driven shafts 20 and 21 to which are secured revolving brushes 22 and 23. Each of said revolving brushes 22 and 23 is provided with a large number of radially extendin resilient wires or combin teeth 24 suita ly formed of steel and aving pointed or sharpened ends which extend through apertures 25 and 26 provided in the surface 3 for that purpose. The hoppershaped bottom 19 opens as at 27 into a assage 28 formed in the base 1 and eXten .ing the full length thereof.

Wood or vegetable stalks is placed in the receptacle 4: lengthwise thereof, so that such wood is subjected to the combing action of the revolving brushes 22 and 23. As these brushes revolve, the combing teeth 2 1 extend through the openings 25 and 26 sufficiently to allow the sharp pointed teeth to engage the wood above said openings. The reciprocation of wood results in a defibering action, whereby the wood is resolved into separate fibers and bundles of fibers which are carried by the revolving brushes into the chamber 18. It should be noted that the brushes 22 and 23 are revolved at a very high rate of speed and that the combing teeth 24: yieldingly engage the wood in the direction of the length of the fibers thereof.

From the chamber 18, the fibers pass through the opening27 into the passage 28, from which the fibers are drawn by means of a current of air induced by a fan 36 through a conduit 31' into a separator 32. The fan may suitably be driven by means of a motor 33. Tn the separator 32, the fibrous material is separated from the air stream and allowed to drop into a charging hopper 34:.

The fibrous material is charged from the hopper 34 into a revolving drum 35 positioned beneath said hopper 'and provided with a manhole 36 for that purpose. drum 35 is provided-with hollow trunnions 37 and 38 mounted in bearings 39 and 10 for revolution, as by means of a driven shaft 41 and a gear 42 acting through a gear ring 43 on said drum 35. Within said drum 35 is mounted a single roller 4.4. of substantially the same length as the length of the cylin drical portion of said drum and freely disposed therein. lindrieal portion of the drum 35 is preferably fitted with longitudinally extending cleats or ribs 45 which, during. revolution of said drum, serve to lift the roller 44 and allow it to drop again onto the fibrous material with which the drum is partially filled. The result is a rolling, kneading and spreading The inner surface of the cy- Said I apart action upon the fibers, which action serves to further disintegrate the fibrous ,bundles and resolve them into the ultimate The other trunnion 37 is likewise providedwith an end thereto.

If hot water only is used as the treating liquid in the drum 35, merely a softening and hydrating action upon the fibers is obtained. However, my invention contemplates the use of either an alkaline or acid cookin liquor similar in composition to any of'the known cooking liquors now in use for the preparation of pulp for use in the manufacture of paper and the if like. Sulphite cooking-acid may, for instance, be introduced into the drum 35 through the pipe 48 in an amount and of a strength sufiicient to completely remove the lignin and incrusting matter from the fibrous material and resolve said material into the ultimate cellulose fibers. To this end, steam may be admitted plate 52 and piping 53 connected 'through the pipe 49 to bring the temperature of the contents of the drum 35to the desired cooking temperature, say between 110 and 150 (3., the steam accordingly being supplied to said drum 35 at a pressure, say from 40 to 7 0 lbs., until the contents of said drum is brought to the desired pressure and temperature to effect cooking of the pulp. The pipe 53 serves as a relief line for the steam, gases and condensate and may be suitregards strength of cooking liquor, temperature, pressures and length of cooking time than where chips are being cooked. In cooking chips by the standard pulping method, penetration of the cooking liquor into the chips takes place only at the ends of the chips, which are frequently sealed as a result of the crushing action of theknives used in the chipping process. The fibrousmaterial used in the present process, on the other hand, being subjected tono cutting or compressing action, and being relatively much more finely divided and in a looser condition, is quickly penetrated by the cooking be produced by the ordinar liquor from the sides as well as from the I asbeing provided only with a'single roller,

it will be understood that a plurality of rollers or rods may be used, as in the ordinary rod mill. I have found, however, that the use of a single roller of relatively large diameter gives much more satisfactory results than the use of a standard rod mill. Furthermore, my process should not be confused with the known processes for the disintegration of partially cooked chips or screenings, where the cooking is carried out in a separate operation and the chips or screenings merely subjected to mechanical disintegration in a rod mill. The use of fibrous'material specially prepared according to my process by subjecting the wood or vegetable stalks to a yielding combing action in the direction of the length of the fibers permits the combination of a mild cooking process with the mechanical process of rolling, kneading and spreading apart the fibers in a single operation. The result is that a well cooked and partially hydrated pulp can IfJe obtained more economically than heretoore.

It will further be understood by those familiar with the art that the fibrous material used in my process cannot be employed in standard digesters due in part to the fact that it would pack too ti htly in the digesters to permit the necessary 5 with the result that a part of the fibrous material would be overcooked or even burned in the cooking process. By using a revolving drum and a single roller, the necessary amount of mixing'of the fibrous material with the cooking liquor is obtained to insure uniform cooking. Where only hot water is used as the treating liquor, an improved quality'of mechanical pulp better adapted for the manufacture of high grade paper than the ground wood pulp at present supegree of circulation,- V

plied to the paper industry is obtained. This my process the fibers are preserved in subf stantially their natural length and integrity.

Furthermore, the rolling, kneading andspreading apart action of the drum and roller in the presence of hot water or steam, gives a softer and better hydrated pulp than can grinding processes. Mechanical pulp ma e in accordance with my process may consequently be used in a larger proportion-in admixture with chemically prepared pulp in the manufacture of Lpaper than can the ordinary I ground woo pulp.

- I am aware that many changes may be. made andnumerous details of construction may be varied through a wide ran without departing from the principles this invention, and I, there ore, do not pur limiting the patent granted hereon ot erwise than necessitated by the prior art.

I claim as my invention: 1 The method of preparing pulp for use in the manufacture of paper and the like,

which comprises treating mechanically disintegrated fibrous material with a sulfite cooking acid at a temperature of between 110 and 150C. and under a pressure of 2 between and 70 lbs. per sq. in. and simultaneously subjecting the fibrous material to a rolling, kneadingmand spreading a art action, said rolling, eading andspreadin 4 apart action being substantlally non-grin 2 ing. a

2. The rocess of preparing pulp from mechanics ly disintegrated fibrous material which comprises treating said material with a liquid in a rotating drum while subjecting 80 the material to rolling, kneading and spreading apart action between the inner surface of the rotating drum and a surface within the drum which is freely rotatable over the material by frictional contact therewith, and

86 intermittently compacting the fibres by raising the freely rotatable surface at predetermmed intervals and allowing it to drop on the material in the drum.

3. The process of conditioning prepared 40 combed fibres which com rises heating said fibres under pressurewit a cooking liquor in a rotating drum and simultaneously subjectin the bres to a rolling, kneading, and sprea ing apart action between the inner surface of the rotating drum and the surface 'of an elongated cylinder within the drum freely rotating in frictional surface contact with the material; In testimony whereof I have hereunto subscribed my name at Chicago, Cook County,

' Illinois.

' UEL S. MoMILLAN. 

